In Vivo siRNA Delivery and Tissue Targeting (In Vivo RNAi)

In Vivo siRNA Delivery and Tissue Targeting

RNAi-induced gene silencing is used to study gene function in cultured cells (in vitro). Most often, these effects are induced by the introduction of small-interfering RNA (siRNA) or microRNA (miRNA). A siRNA molecule is double-stranded and 20-24 base pairs in length, terminating in two overhanging nucleotides with phosphorylated 5′ and hydroxylated 3′ ends. A miRNA molecule is single-stranded and 22 nucleotides long; it binds to a complementary segment of RNA to create a double-stranded molecule. Both of these molecules may occur naturally in the cell as well as being artificially introduced, and their effects may last three to seven days.

However, the in vitro approach does not allow a critical evaluation of gene function within the whole organism, as an in vivo study would. Unfortunately, in vivo RNAi studies present many technical challenges due to siRNA instability, delivery inefficiency, incorrect biodistribution, and the difficulties of targeting specific tissues. These technical challenges mean that performing RNAi experiments in animals can be laborious, time-consuming, and expensive.

Two basic methods are adapted for RNAi use in vivo: administration of siRNA or miRNA and administration of plasmid DNA and viral vectors, which in vivo express a short hairpin RNA (shRNA) that is subsequently processed into active siRNA. In general, viral-based shRNA vectors provide the highest delivery efficiency in vivo, but are time-consuming to construct and have significant immunogenicity problems.

One of the key challenges faced when using RNAi technology is the successful delivery of a stable and functional siRNA or microRNA molecule to the target tissue. The siRNA or miRNA must overcome degradation by nucleases, escape detection by the innate immune system, minimize off-target effects and ultimately be taken up by the target tissue. Altogen Labs has developed methods to prevent siRNA degradation in serum (including both chemical modification and encapsulation of siRNA), increase delivery efficiency to the target organ, and produce strong tissue-targeted functional effects induced by siRNA in vivo.

Chemical modifications of siRNA or miRNA are performed to increase their stability in vivo. These chemical modifications sustain the potency, efficacy and specificity of the siRNA molecules and increase their overall stability in the dynamic environment of a living organism. Standard modifications include 2’MOE, FANA, 2’-Fluoro, LNA, and encapsulation into liposomes.

Two basic methods are adapted for RNAi use in vivo: administration of small interfering RNA (siRNA) and administration of plasmid DNA and viral vectors, which express a short hairpin RNA (shRNA) that is subsequently processed into active siRNA in vivo. In general, viral-based shRNA vectors provide the highest delivery efficiency in vivo, but are time-consuming to construct and have significant immunogenicity problem.

At Altogen Labs, we recognize that providing fast delivery of products and services is critical to expediting research. We are committed to meeting our clients’ timely needs while maintaining high quality and integrity. All of our services undergo rigorous QC procedures.

Once we know the details of your project, we can provide you an immediate price quote (contact us via e-mail at info@altogenlabs.com or call Altogen Labs at 512-433-6177). Please note that experimental details will help us to provide an accurate quote and timeline estimate.

Please send the details of your project to info@altogenlabs.com, or call 512-433-6177 and we will be happy to provide an immediate price quote. Experimental details will help us provide an accurate quote and timeline estimate.